Known in the art are reciprocating internal combustion engines provided with pistons carrying out reciprocal motion inside cylinders, and an output crankshaft.
Also known in the art is a rotary internal combustion engine comprising a hollow torus-shaped working cylinder provided with a water jacket; a through continuous circular slot whose walls are symmetrically disposed relative to the central plane of the cylinder around the smallest-diameter surface thereof; an injector or a spark plug; arc-shaped extended intake and exhaust ports provided in the wall for intake of air or an air-fuel mixture and for exhaust of combustion gases; a circular housing symmetrically disposed relative to the central axis of the cylinder and provided with side walls, mounted in the working cylinder for displacement along the internal surface thereof; four pistons shaped to conform this surface and provided with compression and oil-scraper rings close to ends thereof (U.S. Pat. No. 4,026,249). In addition, this prior art engine is provided with an output shaft mounted for rotation within side walls of the housing about the central axis of the working cylinder and provided with a flywheel disposed symmetrically relative to the central plane of the cylinder; two bearing members disposed on both sides of the flywheel, each of said members comprising radially arranged ring and a disc-shaped C-wall provided with diametrically opposite slots and mounted on the output shaft for rotation thereabout. Two pistons of this engine are fastened in a diametrically opposite relationship on one ring, and two pistons, on the other ring, thereby forming inter-piston chambers between the pistons that are fastened on different bearing members. In such design, shape and size of the rings are chosen proceeding from the condition of their mounting inside the circular slot for tight contact between external surfaces of the rings and compression and oil-scraper rings, and for sealing the gaps between end faces of said rings, as well as between other end faces thereof and circular slot walls. This rotary engine is provided with a transmission gear joining the bearing members with the output shaft and comprising two toothed gearwheels in the form of external-mesh gearwheels that are fastened on the side walls of the housing, four satellite gears coupled with the flywheel, two of said satellite gears being in engagement with one toothed gearwheel and coupled with one bearing member, and two other gearwheels engaged with the other toothed gearwheel and coupled with the other bearing member. The pivot pin of each satellite gear connected with one bearing member is disposed between pivot pins of the satellite gears coupled with the other bearing member. In addition, the engine comprises two eccentric members provided with two main journals mounted for rotation inside flywheel openings, said openings being parallel to the flywheel axis and disposed in a diametrically opposite arrangement on the same circumference, and four crankpins disposed at the ends of the main journals in eccentric arrangement, each said crankpin being passed through one of the radial slots provided in the wall of one of the bearing members, and into the opening of one of the satellite gears. In this prior-art design of the rotary internal combustion engine, the ratio between diameters of satellite gears and toothed gearwheels is 1:2; the planes passing through the axes of main journals and crankpins of each pair of adjacent eccentric members intersect at an angle of 90°, and the distance between the crankpins in the areas of top and bottom dead centers is minimal.
In the above-described rotary engine, all the pistons are rotating in the same direction; in so doing, adjacent pistons are either drawing together or moving away from one another, thereby providing a decrease/increase in the volumes of inter-piston chambers, and thereby ensuring, in the process of rotation of each of the inter-piston chambers, the possibility of executing successive strokes: intake of air and fuel or an air-fuel mixture in the chamber, compression of the air-fuel mixture; ignition of the above mixture accompanied by expansion of combustion gases, and exhaust of said gases from the chamber.
As against a regular reciprocating engine, the rotary engine features the following advantages. First, in the rotary engine all the pistons are disposed within the same cylinder, i.e. they are arranged in the circular rather than longitudinal direction, thereby allowing to reduce longitudinal dimensions of the engine; second, the pistons are moving in the circular rather than radial direction; as a result, the rotary engine is much more compact than the reciprocating one. In addition, arrangement of all the pistons within one cylinder and their rotation in the circular direction result in a lower materials consumption of such engine. At the same time, conversion of rotation of the pistons to rotation of the output shaft is accomplished through the use of four eccentric members rather than via a massive crankshaft, thereby also reducing the materials consumption of the engine. Meanwhile, the major advantage of the rotary engine consists in that its pistons are not reciprocating but rather constantly moving in one direction, although at alternate speeds, thereby resulting in substantially lower consumption of energy required to overcome the inertia of pistons in a change of the sign of their acceleration for an opposite one, and hence in an increase of the engine specific power and performance index. In the rotary engine, supply of air or air-fuel mixture to the cylinder and exhaust of combustion gases are carried out by closing and opening intake and exhaust ports by pistons in the course of their travel within the cylinder, thereby eliminating the need in a complicated multicomponent control gear comprising a camshaft coupled with the crankshaft, as well as lifters, rocker arms, and valves: all this simplifies engine design and improves reliability of its operation, while eliminating consumption of energy for driving this control gear.
However, in the above-described engine the couplings between the flywheel, bearing members, and satellite gears are executed via crankpin—radial slot kinematic pairs that operate under kinetic friction conditions and great contact loads, thereby causing substantial friction in these pairs and resulting in substantial abrasion of the walls of radial slots and crankpins, and hence in an increase of gaps therebetween; all this results in emergence of impact loads that disturb normal operation of the engine. At the same time, satellite gears do not have any axial bearings since these satellite gears are coupled with the flywheel by means of crankpins disposed in these satellite gears in eccentric arrangement relative to the axes of rotation thereof; therefore, the crankpins exert high pressure forces to hold satellite gears together with the toothed gearwheels during rotational movements of the crankpins toward said toothed gearwheels, and pull the crankpins away from the toothed gearwheels during rotational movements of the crankpins in the opposite direction. Such an arrangement creates great radial loads on the satellite gears and toothed gearwheels, and causes fluctuating bending stresses in the crankpins, and hence fluctuating loads on all the components of the transmission gear. Elevated loads in meshes between satellite gears and gearwheels cause substantial friction forces in such meshes, which in addition to substantial friction forces in the crankpin—radial slot kinematic pairs results in considerable losses of energy, and hence in an insufficient performance index of the engine. Considerable loads in meshes, as well as impact loads in crankpin—radial slot pairs result in an inadequate reliability of the engine and insufficient interrepair life thereof. At the same time, rigid couplings between the components of the transmission gear, carried out via two eccentric members, impose restraints on setting a mode of variation of the speed of relative travel of the bearing members, and result in an additional increase in the loads on the transmission gear components.